WASHINGTON – More than a dozen states are moving to strengthen environmental protections to fight a range of problems from climate change to water pollution, opening a widening rift between stringent state policies and the Trump administration’s deregulatory agenda.

In recent months, Hawaii, New York and California have moved to ban a widely used agricultural pesticide linked to neurological problems in children, even as the administration has resisted such restrictions. Michigan and New Jersey are pushing to restrict a ubiquitous class of chemical compounds that have turned up in drinking water, saying they no longer can wait for the Environmental Protection Agency to take action.

Colorado and New Mexico have adopted new policies targeting greenhouse gas emissions from fossil fuel drilling and limiting where these operations can take place. And more than a dozen states have adopted policies that would force automakers to produce more fuel-efficient cars than federal standards require.

The growing patchwork of regulations is creating uncertainty for American businesses as state lawmakers vie to change rules that, in past administrations, were more likely to be set at the federal level.

“At the end of the day, I think regulated entities want to know what the expectations are,” said Wendy Heiger-Bernays, an environmental health professor at Boston University. “They’d prefer not to have two different standards — one in one state and another in another state.”

Local officials say the jumble of policies also threatens to create disparities, not only in obligations placed on businesses but also in the level of protections guarding human health in different areas.

“It is difficult to communicate to your customers that New Jersey or Minnesota or Vermont has evaluated the risk to their residents differently, and that one state places a lower value on protection of public health than another,” Brian Steglitz, the water treatment manager for Ann Arbor, Mich., said last week in testimony before a panel of the U.S. House Energy and Commerce Committee.

Since President Donald Trump took office, his administration has scaled back numerous environmental rules enacted under President Barack Obama and declined to impose federal limits on some contaminants and pesticides. The Trump administration also has reversed course on climate change, refusing to embrace limits on greenhouse gas emissions that the federal government previously had pledged to adopt under an international agreement.

EPA Administrator Andrew Wheeler said the federal government regularly works hand in hand with the states, which often are the more appropriate forum for litigating such environmental matters. For example, he said, the Trump administration has allowed many states to shape their own strategies for meeting air quality standards, rather than imposing a federal plan.

Companies such as 3M, which faces significant regulatory and cleanup costs, also have pressed for a national standard. “We support regulation rooted in the best-available science and believe that this plan may help prevent a patchwork of state standards that could increase confusion and uncertainty for communities,” 3M said in a statement.

“Overall, we try to defer to the states as much as possible,” Wheeler said — though he added that the administration would oppose state action that would “interfere with national commerce” or “create uncertainties for consumers or for businesses.”

At the Interior Department, which controls industry access to vast swaths of public lands, a spokeswoman said the administration views its more business-friendly approach as a key contributor to the nation’s vibrant economic growth under Trump.

“We will continue our work to advance President Trump’s deregulatory agenda, which has boosted the American economy,” she said.